Quarter-wave Retardation Film Research Articles

Beam steering for virtual/augmented reality displays with a cycloidal diffractive waveplate.

We proposed a switchable beam steering device with cycloidal diffractive waveplate (CDW) for eye tracking in a virtual reality (VR) or augmented reality (AR) display system. Such a CDW diffracts the incident circularly polarized light to the first order with over 95% efficiency. To convert the input linearly polarized light to right-handed or left-handed circular polarization, we developed a broadband polarization switch consisting of a twisted nematic liquid crystal cell and an achromatic quarter-wave retardation film. By cascading 2-3 CDWs together, multiple diffraction angles can be achieved. To suppress the color dispersion, we proposed two approaches to obtain the same diffraction angle for red, green, and blue LEDs-based full color displays. Our device exhibits several advantages, such as high diffraction efficiency, fast response time, low power consumption, and low cost. It holds promise for the emerging VR/AR displays.

Optical design for single-mode and single-cell gap transflective liquid crystal displays.

Generally, for transflective liquid crystal displays with different modes and different cell gaps between the refractive and transmissive parts, precise process control to pattern the electrode and match the cell gaps may reduce the yield and thus, require high cost. This paper proposes a simple transflective liquid crystal display with a single-mode and single-cell thickness without a patterned electrode to achieve better productivity. The proposed transflective liquid crystal display consists of three half-wave retardation films, two quarter-wave retardation films, and an LC layer, whose optical performance was confirmed by both simulation and experiment. The optimal optical configuration to obtain an excellent dark state in the visible range was determined by the Mueller matrices calculus, which was applied to each optical component. The calculated and experimental results showed that the proposed transflective LC structure has excellent electro-optical properties and is expected to have many liquid crystal display applications.

Optical Design for Reflective Liquid Crystal Displays

An optical design for a reflective LCD with a thicker cell gap that can have relatively higher productivity was examined theoretically. The proposed LCD was characterized by the optical axes of a half-wave retardation film, quarter-wave retardation film, and LC layer, which are 15°, −15° and 75° with the transmission axis of the polarizer, respectively. The LCs at the dark state lie down on the surface to produce half-wave retardation, whereas they rise up to produce quarter-wave retardation under an electric field in the white state. The proposed optical structure for the reflective LCD shows good dispersion characteristics at both the dark and white states.

Reflective liquid crystal display for better productivity.

Most reflective LCDs so far proposed require a very thin cell gap of approximately 1.5μm to satisfy the quarter-wave retardation condition when used with a half-wave retardation film to obtain an acceptable broadband performance over the entire visible range. On the other hand, the inevitable difficulty associated with precise manufacturing of thin cell gap devices is likely to deteriorate the yield, thereby increasing the production cost. This paper proposes a reflective LCD with a larger cell thickness to achieve better productivity. The proposed reflective LCD consists of a tactically arranged stack of a half-wave retardation film, a quarter-wave retardation film, and a liquid-crystal (LC) layer whose optical performance has been confirmed both by simulation and experiment. The optimal optical configuration to obtain an excellent dark state in the visible range was determined by the Mueller matrices calculus as applied to each optical component. The simulated and experimental results showed that the proposed reflective LC structure has excellent electro-optical properties and is expected to be useful for the next generation LCD industry.

A novel quarter‐wave retardation film for improving viewing angle properties in time‐sequential stereoscopic 3D‐LCDs

AbstractWe have successfully developed a quarter‐wave retardation film (QWF) for wide viewing angle 3D liquid crystal displays (3D‐LCDs) that provides high luminance, low crosstalk, low color change, and low head‐tilt‐angle dependency. It was found that the out‐of‐plane retardation (Rth) of the QWF in the LCD needs to be close to 0 nm in order to improve the 3D display properties at an off‐axis position and that the in‐plane retardation (Re) needs to be adjusted from 120 to 130 nm to achieve low color change with head tilting. We adopted a coating process for making our QWF because of its potential for retardation control. 3D‐LCDs with this QWF whose Rth was nearly zero had high performance and allowed off‐axis other than on‐axis.

Performance analysis of stereoscopic three-dimensional projection display systems

In this paper, several types of conventional stereoscopic projection display systems including the polarization-based, ZScreen-based, LC shutter-based and wavelength multiplex imaging-based have been reviewed and their performances have also been discussed in terms of light efficiency. The results revealed that 55%, 86% and 70% of light loss occurred in the LC shutter-based, ZScreen-based and wavelength multiplex imaging-based stereoscopic projection system, respectively. Meanwhile, in the polarized stereoscopic display system using the Type-1 LCD with the external polarizer, 50% of light loss occurred, whereas in the polarized stereoscopic display system using Type-2 LCD with the half-wave retarder and external polarizer, no light loss occurred. In addition, in the polarized stereoscopic projection system using the Type-1 LCD projector and the quarter-wave retardation film, no light loss also occurred. But in all of these cases, some additional light loss might be expected because of light absorption through the employed optical components. On the other hand, in the polarized stereoscopic projection system using the rotated Type-1 LCD/Type-2 LCD projector and the modified Type-1 LCD projector without the external polarizer, no light loss occurred because no additional optical components for polarization were needed.

Optical modes for direct-view single-polarizer reflective BTN-LCD

Optical modes for the surface-controlled direct-view single-polarizer reflective BTN (bistable twisted nematic) LCD (liquid-crystal display) are derived with the Jones matrix method. The modes show excellent brightness and high contrast ratio. By use of a quarter-wave retardation film in the optical configuration, the contrast can be increased.

Reflective Display Associated with In-Plane Rotation of Nematic Liquid Crystal

We have fabricated a novel reflective nematic liquid-crystal cell driven by a fringe field. In the absence of an electric field, the liquid-crystal molecule is homogeneously aligned and when a fringe field induced by interdigital electrodes is applied, liquid-crystal molecules rotate in plane in the entire whole area. A conventional in-plane switching (IPS) cell was impossible for application to a reflective system due to its low aperture ratio. However, a newly designed fringe-field switching (FFS) cell is possible due to its high transmittance. Furthermore it exhibits a wide viewing angle intrinsically owing to the in-plane rotation of the liquid-crystal director. Several reflective systems with either two polarizers or one polarizer with a quarter-wave retardation film are possible. In this study, we investigate the switching principle of each system and compare their electrooptic characteristics by simulation and experiment.

35.3:Improvement of Transmitted Light Efficiency in SH-LCDs Using Quarter Wave Retardation Films(4) Control of Deffects in LCDs(Session 35))(SID"00 Conference Report)

35.3:Improvement of Transmitted Light Efficiency in SH-LCDs Using Quarter Wave Retardation Films(4) Control of Deffects in LCDs(Session 35))(SID"00 Conference Report)